1. Field of the Invention
This invention relates to pharmaceutical compositions including desmopressin, and more particularly to pharmaceutical compositions including low dosages of desmopressin for treatment of certain human diseases.
2. Brief Description of the Related Art
Desmopressin (1-desamino-8-D-arginine vasopressin, dDAVP) is an analogue of vasopressin. Desmopressin has decreased vasopressor activity and increased antidiuretic activity compared to vasopressin. This pharmacological profile enables desmopressin to be clinically used for antidiuresis without causing significant increases in blood pressure. Desmopressin is commercially available as the acetate salt both in tablet form and as a nasal spray, and is commonly prescribed for voiding postponement, incontinence, primary nocturnal enuresis (PNE) and nocturia, among other indications, including central diabetes insipidus.
Desmopressin has been administered intravenously, subcutaneously, intranasally and orally. The intravenous route of administration is clinically used almost exclusively to treat patients with mild hemophilia or Von Willebrand's Disease to raise blood levels of Factor VIII prior to surgery. Subcutaneous injection is used infrequently and primarily in patients with central diabetes insipidus, a deficiency of vasopressin resulting in the renal production of large volumes of extremely dilute urine which can cause severe dehydration. Intranasal administration of desmopressin via a nasal spray is approved for the maintenance treatment of patients with central diabetes insipidus and in children (ages 6 to 16 years) with primary nocturnal enuresis. An oral tablet dosage form of desmopressin is also approved for the treatment of central diabetes insipidus and primary nocturnal enuresis.
Currently, approved labeling for desmopressin recommends dosing in the following ranges depending on the clinical indication and the route of administration:
Route ofAdministrationClinical Indication(% Bioavailability)Dose Range (daily)Hemophilia/VonIntravenous (100)0.3mcg/kgWillebrand's(21mcg for 70kg patients)Central DiabetesIntravenous (100)2-4mcg qd orInsipidus (CDI)1-2mcg bidSubcutaneous (±90)2-4mcg qd or1-2mcg bidIntranasal (3-5)5-40mcg qd or5-20mcg bidOral (0.1)100-600mcg bidPrimary NocturnalIntranasal (3-5)10-40mcg qhsEnuresis (PNE)Oral (0.1)200-600mcg qhs
The maximum plasma/plasma/serum concentrations achieved with a typical intranasal dose of desmopressin for CDI or PNE of 20 micrograms (mcg or μg) would be approximately 20-30 pg/mL based on 3-5% bioavailability. For the desmopressin oral tablet with only 0.1-0.15% bioavailability, a standard dose of 200-400 mcg would also produce a peak plasma/plasma/serum level of 20-30 pg/mL.
While existing formulations of desmopressin have met the needs of patients, there is still a need for improvement. Tablets are often preferred by patients because of their ease of use, discretion and the lack of uncertainty of correct administration. However, tablets generally need to be taken with a glass of water or other drink, which is a problem as fluid intake needs to be restricted in connection with desmopressin treatment, and the message to the patient is much clearer when there is no water intake at all. In addition, while the above doses and plasma/plasma/serum concentrations are effective for treating CDI and PNE, standard dosages of desmopressin have been shown to cause undesirable side-effects including high incidences of hyponatremia. Lower dosages are preferable if the same desired effect could be produced. However, the current trend in this field is the evaluation of higher dosages of desmopressin for treatment purposes.